Some 600 police officers are being relocated following a midnight purge of 350 officers at the Ankara Police Department in the single biggest wave of a government response to an onging graft probe launched against it, Doğan news agency reported.

The 350 were reportedly working in units specializing in terrorism, intelligence, organized crimes, financial crimes, cybercrimes and smuggling. Around 80 of those dismissed were police chiefs while the others were officers working at lower ranks, it added. The sweep also included a deputy head of Ankara’s police forces.

Some 250 officers have reportedly replaced the relocated officers at the Ankara Police Department.

The sons of two ex-ministers and the general manager of state-owned bank Halkbank remain in custody following the corruption probe, which began Dec. 17, 2013.

In a tit-for-tat response, police officers, including Istanbul Police Chief Hüseyin Çapkın, were sacked or moved to different position on Dec. 22, 2013.

The probe highlighted the deepening conflict between the ruling Justice and Development Party (AKP) and the movement of Islamic scholar Fethullah Gülen, whose followers are said to hold key positions inside the secret services, police and judiciary and are believed to be behind the investigation.

Prime Minister Recep Tayyip Erdoğan and several government officials have repeatedly accused “a parallel state” within the police department and especially the judiciary of plotting the probe.

In a recent letter sent to President Abdullah Gül, Gülen deplored the dismissal of “public workers who had no ties to the recent corruption” while he denied claims that he had influenced state activities or given directives to civil servants in an apparent response to Erdoğan’s claims.